The eye is a specialized sensory organ capable of light reception and able to receive visual images. In the eye, the trabecular meshwork may serve as a drainage channel and may be located in the anterior chamber angle formed between the iris and the cornea. The trabecular meshwork may maintain a balanced pressure in the anterior chamber of the eye by allowing aqueous humor to flow from the anterior chamber. The aqueous humor flows out of the anterior chamber (the space between the cornea and iris) through the trabecular meshwork and the uveoscleral pathways, both of which contribute to the aqueous humor drainage system. The delicate balance between the production and drainage of aqueous humor determines the eye's intraocular pressure (“IOP”).
Glaucoma is a group of eye diseases encompassing a broad spectrum of clinical presentations, etiologies, and treatment modalities. Glaucoma may cause pathological changes in the optic nerve, visible on the optic disk, and it may cause corresponding visual field loss, resulting in blindness if untreated. Most forms of glaucoma result when the IOP increases to pressures above normal for prolonged periods of time. The IOP can increase due to high resistance to the drainage of the aqueous humor relative to its production. Left untreated, an elevated intraocular pressure causes irreversible damage to the optic nerve and retinal fibers resulting in a progressive, permanent loss of vision.
Current therapies for glaucoma may be directed at decreasing intraocular pressure. Medical therapy may include topical ophthalmic drops or oral medications that may reduce the production or increase the outflow of aqueous humor. However, these drug therapies for glaucoma may be associated with side effects, such as, for example, headache, blurred vision, allergic reactions, death from cardiopulmonary complications, and potential interactions with other drugs. Additionally, even at reduced pressure, glaucoma patients may be susceptible to optic nerve damage and vision loss. Normal tension glaucoma may be characterized by damage to the optic nerve without an increase in IOP above physiologically normal levels. Because dropping IOP below physiological conditions may present a risk of hypotony, treatment of normal tension glaucoma may be limited.